(CNN) -- An American man has been detained in North Korea, two State Department officials told CNN.

Diplomatic sources speaking on condition of not being identified said the man is a Korean-American businessman. One of the sources said the businessman had a visa to enter North Korea.

The State Department is working with the Swedish Embassy in the North Korean capital, Pyongyang, the officials said. The United States is urging North Korean authorities, through the Swedes, to release the man on humanitarian grounds.

Sweden represents America's interests in North Korea because the United States and North Korea do not have diplomatic relations.

The Swedes have been granted consular access to the man and have visited him, the officials said. The Swedes are asking for regular visits, the officials said.

A Swedish official in Stockholm confirmed to CNN that the embassy in Pyongyang is working on the case.

The sources declined to provide additional information because of privacy concerns.

North Korea has detained several Americans in recent years, increasing tension levels in what is already a rocky relationship between Pyongyang and Washington.

In 2010, former President Jimmy Carter helped secure the release of Aijalon Mahli Gomes, a U.S. citizen who had been fined roughly $600,000 and sentenced to eight years of hard labor for crossing over the Chinese border into North Korea.

Gomes, who attempted to commit suicide while in North Korean custody, was believed to be a Christian activist.

Two American journalists -- Laura Ling and Euna Lee, who had entered North Korea in March 2009 and were arrested and sentenced to 12 years hard labor -- were released in August 2009 after an intervention by former U.S. President Bill Clinton.

Tensions between North Korea and the West have spiked in recent years due in part to concerns over Pyongyang's nuclear development program. The United States and South Korea held joint military drills in February, despite North Korea's warning to the South not to carry out the drills, calling them a provocation and threatening to engulf Seoul in a "sea of flames."

South Korea accuses the North of torpedoing and sinking one of its warships in March 2010, killing 46 sailors, and last November, North Korea shelled Yeonpyeong Island, killing two South Korean marines and two civilians.